In a statement, Ivanka Trump called Peretti's words "a complete and total lie."

Reached by phone, Peretti said he wrote the tweet in an airport lounge in Burbank, California, after having read a BuzzFeed News report about the daughter of the Republican presidential nominee reacting to a 2005 tape of him making lewd remarks about grabbing women’s genitals.

“That’s not language consistent with any conversation I’ve ever had with him, certainly, or any conversation I’ve overheard,” she said at Fortune’s Most Powerful Women Summit. “So it was a bit jarring for me to hear.”

Peretti said the encounter with Ivanka occurred at a Manhattan dive bar called Tropical 128 about 8-10 years ago with roughly five other people present, including his wife, Andrea Harner. Peretti said Ivanka and he share a mutual friend who invited her to the bar that evening.

“She was saying how she first said she had never seen an uncircumcised cock and then she said, ‘I’ve never seen a mulatto cock. There’s lots of cocks I’ve never seen,’ or something like that,” Peretti said.

“Of course, it was memorable just because of the use of the lewd language and racist language. It was also memorable being in the environment of being… in New York, sometimes liberal and progressive people make comments meant as jokes and not necessarily earnest. I didn’t know how to take it.”

Peretti said that, in the years since the encounter, he and his wife have discussed the alleged quote privately multiple times.

Reached by email, Harner told BuzzFeed News: "I was there and did hear it but have no comment beyond that."

Another person Peretti named as having been there that evening, who wished to remain anonymous, confirmed to BuzzFeed News that the gathering did take place in 2008 but had no further comment.

Joe Scarnici / Getty Images

Ivanka Trump and Nancy Gibbs on October 19, 2016 in Dana Point, California.

Peretti said he “sat” on the quote, not revealing it until now, because it was “personal.”

“I have conversations with people all the time and I never share things said in private. I only shared this because I read the article and it felt like that experience was relevant,” he said.

Ivanka Trump vehemently denied Peretti's words in a statement sent to BuzzFeed News.

"I am not sure if this was meant to be a joke, but in case there is any ambiguity, this is a complete and total lie," she said.

A Donald Trump spokesperson told BuzzFeed News the Republican's campaign is demanding an apology from Peretti.

"What a little man and a disgraceful liar to smear Ivanka Trump like this," spokesperson Jason Miller said in an email. "It shows just how far the media will go to tear down Mr. Trump’s family, and we demand an apology."